For two heart-pumping minutes, the booster for NASA’s new rocket, the Space Launch System, demonstrated its power and operated as planned at nearly 6,000 degrees Fahrenheit during a successful qualification test June 28 at Orbital ATK’s test facilities in Promontory, Utah.
The smoke has well cleared from that test, but critical data continues to pour in, which will help NASA qualify the booster for the first, uncrewed flight of SLS with the Orion spacecraft in 2018 — a key milestone on the agency’s journey to Mars.
“Preliminary analysis from the test shows the instrumentation performed extremely well and gathered the critical data needed to show that we met our test objectives,” said Mat Bevill, deputy chief engineer for the SLS Boosters Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama, where the SLS program is managed for the agency.
During the test, 82 qualification test objectives were measured through more than 530 instrumentation channels on the booster at a cold motor conditioning target of 40 degrees Fahrenheit – which is the colder end of its accepted propellant temperature range.
This is the second qualification ground test for the booster, as the first was successfully completed in March 2015. This is the fifth, full-scale motor test overall for the booster, which includes three development tests. The first qualification ground test demonstrated acceptable performance of the booster design at 90 degrees Fahrenheit — the highest end of the booster’s accepted propellant temperature range. Testing at the thermal extremes experienced by the booster on the launch pad is important to understanding the effect of temperature on how the propellant burns.
“We still have many months to go to analyze all the data from the second test, as it’s a very detailed process,” Bevill said. That process includes disassembling the 154-foot-long booster and getting a thorough look at every part of it. The detailed inspection, including the post-test measurements, will support verification that the booster design meets SLS requirements and performed as expected on test day. Engineers also will compare data from the previous four ground tests.
Once all analysis is complete, the boosters will still have a few steps to go before being ready for the launch pad, including design certification review. That review will determine if the design for all parts of the booster are certified for flight. In 2015, the SLS Program completed its critical design review – a first in almost 40 years for a NASA human-rated rocket.
“This is a critical and exciting time for our teams as we prepare the boosters for flight and move forward on the journey to Mars,” said Alex Priskos, manager of the SLS Boosters Office. “Booster flight hardware for our first flight, Exploration Mission-1, is in full production, with four segments being cast and a fifth going to casting later this month at Orbital ATK. We also have aft skirt refurbishment work taking place at Kennedy Space Center, where the boosters will be stacked ahead of the flight.” Orbital ATK, headquartered in Dulles, Virginia, is prime contractor for the SLS boosters.
When completed, two five-segment boosters and four RS-25 main engines will power the SLS on deep space missions. The solid rocket boosters operate in parallel with the main engines for the first two minutes of flight. They provide more than 75 percent of the thrust needed for the rocket to escape the gravitational pull of Earth.
The initial SLS configuration will have a minimum 70-metric-ton (77-ton) lift capability. The next planned upgrade of SLS will use a powerful exploration upper stage for more ambitious missions with a 105-metric-ton (115-ton) lift capacity. In each configuration, SLS will continue to use the same core stage and four RS-25 engines.
